Biofilm formation on aluminum alloy 2024: A laboratory study

• Biofilm formation on aluminum alloy AA2024.
• Consortia constituted by Bacillus subtilis and Bacillus circulans.
• Evident corrosion processes measured by microscopic and electrochemical techniques.

In this paper we studied the influence of bacterial consortia on corrosion of fuel tanks of aircraft used often for pilot training. In the first part, we proceeded to the isolation and characterization of the consortia by DNA sequencing. The consortium was mainly constituted by two bacteria, which have a close affiliation to Bacillus subtilis and to Bacillus circulans.The substrate used in fuel tanks was an aluminum alloy 2024. Electrochemical measurements and morphological characterization were performed for different immersion times (1, 2, 3, 7 and 14 days) in sterile minimal salt medium (MSM) and in inoculated media (MSM + B.subtilis and MSM + consortia). For all immersion times, impedance diagrams showed a capacitive behavior characterized by a single constant time. Although for short exposure times, no corrosion process was evidenced, for longer exposure time, the resistance of the aluminum oxide (Rox) decreased markedly, indicating that a corrosion process was taking place.